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Topic Review (Newest First)

06-15-2002 11:49 AM

mad van

hi as i have experianced this myself.i suggest you might have the same problem, after having my engine eat 3 cams i had my lifter bores checked they were out.i tossed the engine only to get another block with lifter bores out of aliment,not by little but heaps.i had kept the old lifters in order to referance back .put new rings,bearings,cam and lifters and run in as per usual proper cam manufacturs recomendations.60 miles and cam was for the scrp heap .so i checked the old with new lifters and they correspond with marks in old lifters.so i had the block lifter trued and now is fine.hope this is of some help.

06-12-2002 12:46 PM

Lloyd Topping Jr

With 1.6 Rocker arms you are running into coil bind.Clay your pistons and make sure you have plenty of piston to valve clearance - .080 to .100 on the exhaust valve. The intake valves should never hit - piston is going down as the valve is opening. When the exhaust valve is all the way open you should be able to put a .050 feeler gauge between the coils in the springs. Check the installed height of the valve springs.Measure from the bottom of the spring pocket to under side of the valve spring retainer, where the top of the spring rides.

06-12-2002 12:12 PM

Al Mather

lots of good ideas.anyway run the engine with out a valve cover,make sure push rods are rotateing,and oil is coming up,i think if you had a binding problem,push rods would go first.cam walk is a possibility,check your chain cover.good luck.

06-11-2002 09:14 PM

Nasty Nova

E, I don't know what your problem is, but I had a similar problem on my 355 Chevy. It ate 2 hydraulic cams. I went with a 280/290 solid lift cam (.520-.521) (2500-7000 RPM) from Herbert Performance, and have run it over a year now without any problems (that includes over 200 passes at the strip). Never did figure out what the problem was with using the hydraulic cams.

06-11-2002 03:23 PM

hogerdoger

I had the same problem with a comp cam, and I also followed the breakin to a T. I was told by a guy at the local rod shop that he also went thruogh 3 comp cams with the same outcome. Don't know for sure but I heard comp cams is farming out thier grind work and quality control is suffering. My solution was to boycott comp cams and switch to Isky. Comp cams had poor customer service. They would replace the cam for me but offered no reason for the failer. Thier attitude seemed like they get flat cam calls all day long. Call Isky and you'll get someone who really wants to help with all your cam troubles. No I don't have stock or work for Isky, but thier cam works good for me.

06-11-2002 03:10 PM

bullheimer

dont have a clue what's causing this but i don't think you have to. you said a quality shop did the machine work on the heads. that means you take the heads right back there and have them do all the explaining or you shove them done their throats.

06-09-2002 09:26 PM

eblyon

Thanks for all your replies I'll do some more checking on your suggestions .I've been bussy setting up my new garage with electricity,water and what not. I'll post another message on what I find. It may be a few days. Thanks again and if anyone else has a suggestion feel free to post a reply.

06-09-2002 12:37 PM

4 Jaw Chuck

I just thought of one more thing, did you find any slightly bent pushrods? This would indicate a binding/clearance problem.

06-08-2002 08:09 PM

JdOwNj

Hate to point out the obvious, but have you checked piston to valve clearance?

06-08-2002 12:17 PM

78 monte

Do you have oil restrictors in this engine? That could be it if its killed 2 cams in 10,000mi.

06-08-2002 10:18 AM

HQ Pete

ive learnt alot from 4 jaw chuck(that man is a machine) and he has good reason to suspect bearing clearances.might this be due to the rear lobes going fisrt maybe ?

06-08-2002 10:02 AM

4 Jaw Chuck

Eblyon, what was the clearance on the cam journals? HQ Pete has some good advice on the clearance for the springs and valve train.

06-08-2002 09:56 AM

HQ Pete

ps...if you have the right rpm for breck-in ,heaps of lube ,and no machanical bind of any sort there sould be no reason why its eating lobes ,and just something else i thought i'd throw at ya is wot about the cam chain gear or sprocket is it new ? if so make sure the cam is going the full distance back into the block so its running on the lifters correctly and it should spin freely in there. i'm sorry for the double post ,i just had to get it out tho ..

06-08-2002 09:45 AM

HQ Pete

ok that cam sounds ok but maybe the rocker ratio is too much .507/.510 lift.....is it just the exhaust lobes that are gone or intake as well ?...i would check the valve lift without a spring on there ,if its not coil bind then maybe it is bottom of spring retainer hitting on valve guide .it might just be that extra .010" lift that puts the damageing presure on the lobes ....i have preasures for a 272-h10 and they are 105lb closed 265 open but theres alot more too it than that (installed height and all that stuffs)sounds like your pretty on to it with the breckin procedure.seems strange that its the back cylinders with most wear(#8,7,6,5).i would look at simulating the lift on inlet and speaclly the exhaust without a spring in there and see wots going on .i have a set of gm 041 heads with a .467 exhaust lift and the spring retainer only just clears the guides with valve stem seals,depending on your installed height and rocker ratio this could be a problem . these are just suggestions and hope some else can shed some more light on the subject ....good luck ,get back to us soon

06-07-2002 08:57 PM

eblyon

my engine has around 10,000 miles on it since it was bored and new cam bearings installed. Also I did use new lifters with both cams. I also inspected the cam bearings and they looked fine. Thanks for your replies. I was searching for more power with the cam & head swap.

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